Digital images are formed from an array of pixels (picture elements), each pixel having an assigned color and intensity. Digital images may be processed in a variety of different ways to achieve any number of desired effects.
For example, digital images may be processed to conform to the format of a particular output device (e.g., a printer or plotter). Typically, an image must be converted into a halftone image before it may be printed by an output device. Halftoning is the process of breaking down a continuous tone image into solid spots of differing sizes to create the illusion of transitioning grays or colors in a printed image. Halftones may be created by different methods, including error diffusion, dot pattern, random dither and ordered dithered methods. Each halftone processing method involves converting continuous tone image data into a plurality of binary halftone dots with a density gradation that is similar to that of the original continuous tone image.
Digital images also may be processed to alter their appearance. For example, a digital image may be filtered to add one or more different effects, including fine arts and hand drawn effects, impressionistic and mosaic effects, noise effects, lighting effects, and distortion effects. Adobe™ Photoshop™ (available from Adobe Systems, Incorporated of San Jose, Calif.) provides a halftone pattern filter that applies halftone line pattern effects to an image. Other appearance-altering digital image processing techniques are known.